In the reconstituted Na-K pump, 3 Na ion are transported in and 2 K ion transported out. With the use of 86CL-, attempts will be made to see if 1 Cl- accompanies 3 Na ion to maintain electroneutrality. The glycoprotein subunit of the Na,K-ATPase can be isolated in its "native" form by digestion of the catalytic subunit away with trypsin. The effects of insertion of the glycoprotein in liposomes with and without Na, K-ATPase will be studied on active and passive transports of Na ion and K ion. The 12,500 MW peptide seen on SDS-PAGE gels of purified Na,K-ATPase, which labels its photoaffinity derivatives of cardiac glycosides will be isolated, and its effects on active and passive transports of Na ion and K ion will be investigated in liposomes with and without Na,K-ATPase present. Unequivocal demonstration of the quarternary structure of the Na,K-ATPase will be carried out by labelling all half-cysteine residues of each subunit with radioactive NEM or iodoacetamide. The role of phospholipids (particularly phosphatidic acid and phosphoinositide, which are involved in the "phospholipid effect" in salt glands on stimulation with agonists) will be studied by making liposomes with dioleyl phosphatidyl choline containing small amounts of the above phospholipids as well as other phospholipids of interest. These studies will attempt to get at the role of phospholipids in modulating the Na-K pump.